1. Field of the Invention
The present invention is broadly concerned with solid, high specific gravity, low solubility well treatment composites used for oil and gas well and pipeline treatments. More particularly, the composites of the invention have a high melting point, thus eliminating the problem of ambient air melting, are sufficiently dense so as to readily sink in typical well fluids, and have a low solubility that generates a slow release of the composite ingredients into well or pipeline fluids. The composites of the invention preferably comprise a nonylphenol ethoxylate and a fatty acid amide, and also further include a weighting agent such as barium sulfate, sodium chloride, or sodium bicarbonate, and active ingredients selected from the group consisting of corrosion inhibitors, scale inhibitors, bactericides, scale converters, foaming agents, and mixtures thereof. In one embodiment, the composites are formed into spherical bodies having a maximum surface-to-surface dimension of about 2 inches for use in treating and maintaining oil and gas pipelines.
2. Description of the Prior Art
Oil and gas wells and pipelines require the periodic addition of treatment agents, such as scale and corrosion inhibitors, in order to facilitate smooth, trouble-free operations. In wells, such agents are often in liquid form, and are commonly added into the annular space between the well sidewall and the internal well casing. Well operators use a number of expedients for such additions, such as introduction through a side arm flush associated with the well fluid removal system. Because conventional treating agents tend to float on the well fluid, it is a common practice to add excess well fluid after addition of the treatment agent in order to drive the agent downwardly to a subterranean level adjacent the lower end of the well casing. As can be appreciated, this practice largely or completely shuts down well production, and it is not uncommon to thereby lose an entire day's production during the treatment process.
The foregoing difficulty is particularly acute in the case of low fluid wells having a relatively low static fluid level, in that relatively large amounts of fluid must be added atop the agent in order to drive the agent down to an operative level. However, the problem can also be significant in high fluid wells, because of the need to drive the active chemical downwardly through relatively long columns of fluid. Indeed, it is sometimes impossible in such situations to drive the chemical down far enough into the well formation, and the chemical may be significantly diluted before it reaches the downhole pump.
Weighted treatment agents have been used in the past in an effort to overcome this problem. These materials are in fluid form, but include glycerine or molasses in order to give the fluid a higher specific gravity. Unfortunately, this tends to be an expensive process, and such weighting agents have a tendency to adhere to the outside of the well tubing and casing.
Solid composites have also been utilized to provide a method for downhole treatment. For example, mold inhibitors such as the commercial product Iconol NP-100 Pastille FD (a nonylphenol ethoxylate available from BASF Corp.) have been mixed with active ingredients (such as corrosion inhibitors or bactericides) and formed into pellets. The melting point of NP-100 is approximately 69.degree. C. However, when the active ingredients are added to NP-100 and the mixture is formed into pellets, the melting point of the entire pellet composite is only about 54.degree. C. This results in pellets which melt easily in hot weather and dissolve quickly downhole.
Oil and gas pipelines typically span for hundreds of miles underground from the oil or gas source to various points of delivery. Treating and maintaining these pipelines is particularly critical as repairs are difficult and costly. If a portion of a pipeline is corroded or if flow is being impeded by scale build-up, pipeline operators must first locate the problem area. Once the problem is located, the ground around that section of the pipeline must be excavated and the pipeline repaired or replaced. This shuts down oil and gas delivery for some time and is particularly problematic when the problem area is located under an urban area or in an isolated area such as a dessert.